Outline

Outline is the keystone of any toon stack — a hard ink stroke around the silhouette of a mesh. Genesis ships an inverted-hull outline as a second material pass, plus a renderer-feature module for screen-space outlines when you need pixel-perfect edges.

Video

A toon character orbited by the camera so the inverted-hull outline traces the silhouette and stays consistent as the view distance changes.

features/outline/outline-orbit.mp4

The inverted-hull outline tracing a toon character's silhouette.

When to use it

Toon characters — the canonical anime ink line.
Comic and illustration — pairs with Posterize for the full comic stack.
Gameplay readability — outline enemies in tactical games.
Selection feedback — a runtime-toggleable outline for picked units.

Inverted hull vs screen-space

Inverted hull is per-material, scales with distance, and respects mesh normals — great for characters. Screen-space (a renderer feature) runs on the depth and normal buffers in post and gives consistent one-pixel edges, but requires the module to be installed.

Modes

Inverted hull — a second pass expands the mesh along its normals by _OutlineWidth, flips the cull mode to Front, and writes the outline color. Width scales with camera distance.
Screen-space (via module) — runs as a renderer feature on the depth and normal buffers, holding a steady pixel width regardless of distance. Genesis drives both modes from the same color and width properties.

Screenshot

Side-by-side of the same mesh with an inverted-hull outline (width scaling with distance) and a screen-space outline (constant one-pixel edge), labelled Inverted hull and Screen-space.

features/outline/outline-modes.png

Lit material with no edge stroke.

A crisp black outline tracing the silhouette, scaled by camera distance.

Off

Inverted hull · black

The same material with and without the inverted-hull outline. Drag to compare.

Properties

Inspector label	Shader property	Type	Default	Description
Enable Outline	_OutlineEnabled	Toggle	Off	Master toggle. Adds a second mesh pass.
Outline Color	_OutlineColor	Color	RGB(0,0,0)	Ink tint written by the outline pass.
Outline Width	_OutlineWidth	Float (0–0.05)	0.004	World-space hull offset.
Fade Start	_OutlineFadeStart	Float (0–100)	5.0	Distance where the outline begins to shrink.
Fade End	_OutlineFadeEnd	Float (0–100)	30.0	Distance where the outline disappears.
Noise	_OutlineNoise	Float (0–1)	0.0	Sinusoidal width wobble for a hand-drawn feel.
Z Offset	_OutlineZOffset	Float (-1–1)	0.0	Depth bias to push the outline behind or in front of the mesh.
Use Vertex Color	_OutlineUseVertexColor	Toggle	Off	Multiplies width by vertex-color R for per-vertex painting.

Usage

Enable Outline and pick a color (black is classic; a warm dark brown reads softer).
Set Width between 0.002 and 0.008; too high and the outline pokes through the mesh.
Tune Fade Start / End so the outline disappears at gameplay distance.
For a hand-drawn feel, set Noise to 0.1–0.3.


material.SetFloat("_OutlineEnabled", 1f);
material.SetColor("_OutlineColor", new Color(0.05f, 0.05f, 0.1f));
material.SetFloat("_OutlineWidth", 0.005f);

Tips & gotchas

Hard-edged meshes split the outline: vertices at hard edges have duplicate normals, so the hull tears. Use the Mesh Utility to bake soft normals into UV3 or tangents.
The outline does not respond to lighting by design — it is an ink stroke, not a shaded surface.
Inverted hull adds a full extra draw. Group outline-eligible objects into one render layer to keep batching tight on mobile.
Pixel-width screen-space outlines need adjustment for per-eye resolution in single-pass stereo.

Cel Shading — outline plus cel is the canonical toon stack.
Screen Space Outline Module — post-effect alternative.
Mesh Utility — bake soft normals to fix hull tears.
Rim Lighting — soft fresnel pairs with the hard outline.